Control mechanism for mechanical refrigerating apparatus



July 18, 1933. M, SPREEN 1,919,078

CONTROL MECHANISM FOR MECHANICAL REFRIGERATING APPARATUS Filed Oct. '7. 1927 Maxwefl H. preen Inventor Attorneq Patented July 18, 1933 UNI-TED STATES PATENT OFFICE MAXWELL H. SPREEN, F DETROIT, MICHIGAN, ASSIGNOR TO KELVINATOB CORPORA- TION, OF DETROIT, MICHIGAN, A CORPORIATION OF MICHIGAN CONTROL MECHANISM FOR MECHANICAL REFRIGERATING APPARATUS Application filed October 7, 1927.

My invention relates to mechanical refrigerating systems and it has particular relatlon to a novel method of controlling the operation thereof.

Heretofore, it has been customary, in the mechanical refrigerating art, to control the operation of the motor which drives the compressor by means of an electrical switch operated by a thermostat disposed within the refrigerator. This type of control is satisfactory under ordinary circumstances but under certain circumstances, such for example, as a refrigerator disposed in an unheated room during the winter months, the temperature of the refrigerator is sufiiciently low to prevent the thermostat from starting the compressor motor but is, nevertheless, too high to freeze water. This condition is objectionable because it is then impossible to freeze the ice cubes which are desirable for table use.

By my invention I have eliminated this objection and have provided means adapted to operate in conjunction with the thermostat to cause it to operate to both energize and deenergize the motor under the circumstances indicated.

One object of my invention consists in providing novel means whereby the functioning of a thermostat in a mechanical refrigerating system at regular intervals is insured.

Another object of my invention is to provide means for producing abnormal temperature conditions adjacent the thermostat without substantially affecting the temperature of the refrigerator as a whole.

A further object of my invention consists in providing means for causing the thermo- 'stat to actuate the motor at intervals irrespective of the temperature of the ambient medium while permitting the thermostat to regulate the length of the period of such operation.

A further object of my invention is to provide means for insuring that the temperature of the refrigerator is reduced to the lower limit of the range of the thermostat at intervals.

For a better understanding of my invenstalled therein, and

Serial No. 224,544.

ating system embodying my invention in- Fig. 2 is an enlarged fragmentary partially cross-sectional view of the motor control equipment illustrated in Fig. 1.

My invention is herein shown as applied to a mechanical refrigerating unit consisting of refrigerant expansion apparatus 11 mounted in a refrigerating compartment 12 of a domestic refrigerator cabinet 13, in which is disposed a brine tank 14. The tank 14 is provided with a recess 15 for the reception of trays 16 for the formation of congealed fluid under the-action of the refrigerant expansion apparatus 11, and encloses a refrigerant expansion coil 17 disposed within the brine tank and encircling the recess 15. An expansion valve 18eis connected to an inlet end 19 of the expansion coil 17 and is secured to the top of located at any suitable point, comprises a compressor 24 having an inlet port 25, connected, by means of a duct or tube 26, to an outlet end 27 of the coiled tube 20; A refrigerant condenser 28, having one end 29 thereof connected to an outlet port 30 of the compressor 24 has its other end 31 connected, by

means of a duct or tube 32, to the expansion v valve 18. An electric motor 33 operates the compressor 24 by means of a suitable belt 34.

The motor control mechanism comprises a switch blade 35 pivotally mounted upon an insulatingswitch base 36 by means of a stud 37, and is operated by the bellows 23 of the thermostatic unit 22 between a lower position contacting with a contact clip 38 mounted on the base 36 by means of a stud 39, and an upper position contacting with an upper clip 40 mounted on the base 36 by means of a stud 41. The blade actuated by means of a spring 35 mounted upon a guide rod 35, which in turn is pivotally mounted upon a vertically slidable member 23 connected to the bellows 23. As the pivotal connection between the guide rod 35 and the member 23 is moved by the bellows 23 to a point above the stud 37 the spring 35 forces the blade out of contact with the contact clip and into contact with the contact clip 38. In like manner, when the member 23 is moved downwardly by the bellows 23 the spring 35 moves the arm 35 out of contact with the clip 38 and into contact with the clip 40.

By means of the stud 39 the contact clip 38 is electrically connected to a conductor 45, the stud 37 connects the blade 35 to a conductor 43, and the stud 41 connects the contact clip 40 to a conductor 46. Secured to the thermostat adjacent to the bellows 23 is an electrical heating unit 42, which is enclosed within a protective casing 42 and to one end of which the conductor46 is connected through a manually operable contact switch 55. The opposite end of the heating unit is connected to a conductor 47. The three conductors 43, and 47 extend through an armored conduit to a point adjacent the motor at which point the conductor 43 is connected to one side.of an electrical circuit by means of-a conductor 44, and the conductor 47 is connected to the opposite side of the electrical circuit by means of aconductor 51. The conductor 45 is connectedto one terminal of the motor 33 and the opposite. terminal of the motor is connected to the conductor 47 as indicated at 48'by means of a conductor 49.

Having described the construction of an apparatus embodying my invention, its operation is as follows Assuming that the refrigerator has reached the uppermost limit of the range of the thermostat, expansion of the bellows 23 raises the member 23 causing the blade 35 to move into engagement with the contact member 38. When the switch blade 35 engages the contact 38 a circuit is completed from conductor 44, through conductor 43, stud 37, switch blade 35, con

tact clip 38, stud 39, conductor 45, the motor 33. and conductor 49 to conductor 51, thus energizing the motor and operating the compressor 24. When operation of the compressor 24 has, through the agency of the ex ansion coil 17 reduced the tem erature '0 the refrigerator to a sufiicient (figree, the contraction of the bellows 23 draws the member 235 downwardly, thus causing the switch blade 35 to break contact with the contact clip 38 and engage the contact clip 40. A circuit is thus completed from conductor 44, through conductor 43, stud 37, switch blade 35, contact clip 40, stud 41, conductor 46, switch 55, heating coil 42 and conductor 47 to conductor 51, thus de-energiz ing the motor and causing a current to flow through the heating coil 42. The heating coil 42, being disposed adjacent the bellows 23, transmits the major portion of its heat thereto and raises its temperature without materially raising the temperature of the refrigerator as a whole.

The result of this arrangement of parts and circuits is that, irrespective of the temperature of the room in which the refrigerator is placed, the heating coil 42 causes intermittent energization of the motor, thus insuring that the refrigerator temperature will reach the lower limit of the range of the thermostat, so that ice will be formed in the freezing tray under any and all conditions. During the warm months of the year the heating action of the coil 42 is, of course, not required. In order that unnecessary heat may not be admitted to the refrigerator under these conditions themanually operable switch s manipulated in such manner that the circuit through the conductor 46 to the heating coil 42 is broken, thus permitting the operation of the refrigerating apparatus in the usual manner.

Although I have illustrated but one form ofmy invention and have described in detail but a single application thereof, it will be apparent to those skilled in the art, that various modifications and changes may be made therein without departing from the spirit of my invention or from thescope of the appended claims.

What I claim is:

1. In a mechanically cooled refrigerator, a thermostat responsive to the temperature of the refrigerator and operating to automatically regulate the temperature Within said refrigerator, and means operatively associated with the cooling mechanism for whanging the temperature of the medium surrounding the thermostat.

2. In a mechanically cooled refrigerator, a thermostat responsive to the temperature of the refrigerator and operating to automat pallv regulate the temperature within said refrigerator, and heating means disposed in heat transferring relation with said thermostat.

3. In a mechanically cooled refrigerator, a

thermostat responsive to the temperature of the refrigerator and operating to automatimostat, and means for rendering said heating means ineffective.

In combination in a refrigerator, a mechanical, refrigerating system comprising a compressor, an electric motor for driving said compressor and a cooling unit, said unit being disposed within the refrigerator, a thermostat disposed within the refrigerator and adapted to control the operation of the motor in accordance with .temperature conditions within the refrigerator, and heating means disposed within the refrigerator immediately adjacent the thermostat and adapted to the temperature of the refrigerator immediately adjacent the thermostat.

6. In combination in a refrigerator, a mechanical refrigerating system comprising a compressor, an electric motor for driving said compressor and a cooling unit, said unit being disposed within the refrigerator, a thermostat disposed within the refrigerator and adapted to control the operation of the motor in accordance with temperature conditions within the refrigerator, and heating means disposed within the refrigerator adjacent the thermostat.

7. In combination in a refrigerator, a mechanical refrigerating system -comprising a compressor, an electric motor for driving said compressor and a cooling unit, said unit being disposed within the refrigerator, a thermostat disposed within the refrigerator and adapted to control the operation of the motor in accordance with temperature conditions within the refrigerator and heating means disposed within the refri erator adjacent the thermostat and means or automatically energizing said heating means when the motor is de-energized.

8. In combination in a refrigerator, a mechanical refrigerating system comprising a compressor, an electric motor for driving said compressor and a cooling unit, said unit being disposed within the refri erator, a thermostat disposed within the re ri erator, and a heating element disposed wit in the refrigerator adjacent the thermostat, an electrical switch operably connected to said thermostat, said switch being adapted to control the energization of the motor and the heating coil.

9. In combination in a refrigerator, a mechanical refrigerating system comprising a compressor, an electric motor for driving said compressor and a cooling unit, said unit being disposed within the refri erator, a thermostat disposed within the re rigerator, and a heating element disposed within the refrigerator adjacent the thermostat, an elec trical switch operably connected to said thermostat, and electrically connected to both the heating coil and the motor, and being adapted to automatically deenergizc the motor and energize the heating coil when the thermostat reaches a predetermined low degree of temperature and to de-energize the heating coil and energize the motor when the thermostat reaches a predetermined high degree of temperature.

10. In combination in a refrigerator, a mechanical refrigerating system comprising a compressor, an electric motor for driving said compressor and a cooling unit, said unit being disposed within the refrigerator, a thermostat disposed within the refrigerator, and a heating element disposed within the refrigerator adjacent the thermostat, an electrical switch operably connected to said thermostat, and electrica 1y connected to both the heating coil and the motor, and being adapted to automatically de-energize the motor and energize the heating coil when the thermostat reaches a predetermined low degree of temperature and to de-energize the heating coil and energize the motor when the thermostat reaches a predetermined high degree of temperature, and manually actuated means for rendering said heating coil inoperative.

11. In a mechanically cooled refrigerator, a cooling apparatus comprising a closed refrigerant fluid circulating system, a condensing unit, a motor for operating the condensing unit, a heating coil for increasing the temperature of the refrigerant fluid, and means for electrically energizing the motor and the heating coil alternately.

MAXWELL H. SPREEN. 

